Processing method of capacitor type MEMS sensor and sensor structure

Abstract

The invention provides a processing method of a capacitor type MEMS sensor and the capacitor type MEMS sensor. The method adopts a SON (silicon-on-nothing) technology to perform single-faced processing to obtain two layers of silicon films to be used as two electrodes of a capacitor, and measures pressure by utilizing capacitance change brought by shape change after the lower silicon film is pressed. The processing method can be implemented with an IC production line and does not need extra equipment or non-CMOS production line technology, such as anodic bonding. The processing method of the invention facilitates the control of the consistence of the performance of sensors on a whole wafer.

Description

technical field [0001] The invention relates to the technical field of semiconductor equipment processing, in particular to a processing method and sensor structure of a capacitive MEMS sensor. Background technique [0002] In the prior art, the production of capacitive MEMS sensors usually adopts anodic bonding process. Although the process is relatively mature and simple, the large difference in thermal expansion coefficient between silicon and glass will affect the performance of the device, resulting in a large temperature drift of the sensor. Moreover, the anodic bonding process is not a standard CMOS process. Glass generally cannot be taped on a CMOS production line because it contains conductive ions, so the process needs to be outsourced, making it difficult to monitor the quality, and investing in corresponding equipment will increase investment in fixed assets. [0003] In other production methods, a piezoresistive detection structure is formed. Compared with piezo...

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Problems solved by technology

[0002] In the prior art, the production of capacitive MEMS sensors usually adopts anodic bonding process. Although the process is relatively mature and simple, the large difference in thermal expansion coefficient between silicon and glass will affect the performance of the device, resulting in a large temperature drift of the sensor.

Moreover, the anodic bonding process is not a standard CMOS process. Glass generally cannot be taped on a CMOS production line because it contains conductive ions, so the process needs to be outsourced, making it difficult to monitor the quality, and investing in corresponding equipment will increase the investment in fixed assets.

[0003] In other production methods, a piezoresistive detection structure is formed. Compared with piezoresistive detection, the signal noise of capacitance detection is low and the signal-to-noise ratio is high. However, piezoresistive devices are difficult to achieve due to their inherent thermal noise. Sensor device with high signal-to-noise ratio

Secondly, the capacitance detection scheme is less affected by temperature, and because temperature has a greater influence on piezoresistance, the output results vary greatly with temperature, which increases the difficulty and cost of subsequent chip temperature compensation

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